The present invention relates to vertical tube heat exchangers and evaporators, and more particularly to liquid distributors therefor which are fabricated of an elastic material of sufficient resiliency to provide recovery of the distributor to its original size and form when removed from the tubes of the exchanger or evaporator even after sustained use.
Conventional vertical tube heat exchangers or evaporators known to me include a shell enclosing a top tubesheet, a bottom tubesheet in spaced apart, parallel orientation to the top tubesheet, and parallel liquid flow tubes extending between the top and bottom tubesheets, a rigid liquid distributor inserted into the open top ends of the tubes. The tubes are connected to the tubesheets by various methods such as expansion, welding or a combination of expansion and welding. Due to the manufacturing methods used to expand or weld the tubes to the tubesheet, significant dimensional variations can occur at the open top ends of the tubes. Further, when welding is used to attach the tubes to the tubesheets, high and low spots, and weld overhang can occur which will result in a tube opening which is rough, or irregular in peripheral shape, or out of round even if smooth and regular in peripheral form, as well as being over-sized or undersized from nominal. A mixture of these conditions can occur from tube to tube across the tubesheet. These conditions obviously create numerous production problems in the manufacture of vertical tube heat exchangers. One problem is that a necessary peripheral seal between the rigid liquid distributor device inserted into the top open tube end may not be created thereby allowing liquid to leak between the distributor and tube end resulting in a destruction of the desired smooth spiral flow pattern of liquid from the distributor into and downwardly through the tubes. When the open tube end is irregular, either in shape, size, but most especially when the irregularity is caused by weld overhang, weld start and stop irregularities, or when the open tube end is undersized, it is extremely difficult to insert the distributor into the open tube end and obtain a seal between the distributor and periphery of the open tube end. In many such cases, in order to insert the distributor into the open tube end to a proper depth therein and so that an adequate peripheral seal is created, the distributor must be violently forced into the open tube end by repeated hammer blows. This can result in damage to the distributor. As a further consequence of forcing the distributor into the open tube end, removal of a distributor for cleaning or other maintenance service can be extremely difficult and often results or requires the destruction of the distributor. A further problem, particularly when the tube irregularity is an oversized open tube end, or a weld start and stop irregularity, is that the distributor will frequently pop or vibrate out of the open tube end during either shipment of the heat exchanger or operation of the heat exchanger under turbulent flow conditions.
Examples of various known vertical tube heat exchangers and distributors used in such heat exchangers are shown in the following U.S. Patents:
______________________________________ U.S. Pat. No. Issued To ______________________________________ 2,424,441 July 22, 1947 Edmonds 2,949,935 August 23, 1960 Edmonds 3,016,067 January 9, 1962 Edmonds 3,934,574 January 27, 1976 Johnson 4,134,939 January 16, 1979 Zardi 4,135,597 January 23, 1979 Mattern 4,154,642 May 15, 1979 Mattern 4,199,537 April 22, 1980 Zardi 4,248,296 February 3, 1981 Jezek 4,572,287 February 25, 1986 Allo ______________________________________
To the best of my knowledge, all heretofore known distributors have been fabricated of metal or rigid plastic.